I just resealed the intake manifold and did the tb bypass at the same time. Car runs much better except it overheats now. It never did this before. I did drain the radiator like a dumbass in the process. I filled it back and let it run with the cap open. It went down a few times then wouldn't take anymore. I could only get half a bottle in it. The thing that has me most worried is when it over heated you could smell anti-freeze and it was smoking from back of engine on passenger side. I could also hear what sounded like water draining then it would smoke again. Temp got to the 3rd line the one after halfway on temp gauge. Sat for 20 minutes with hood up then drove home. It didn't have time to heat up again. I really need some help with....... car is 95 z28 6 speed

 

LT1 motors are reverse cooling so unlike other cars you need to bleed air from the cooling system if you open it and drain fluid out, replace water pumps or....do TB bypass mod.

There is a small brass bolt on the thermostat housing, that is the bleed screw. slightly raise the front of the car (can even park on a slight incline) and with the cooling tank resevoir filled to the full mark start car and let warm up to when the thermostat opens. Best to stuff rags around the bleed screw first so you don't dump coolant on Opti. losen bleed screw and coolant should putter out and when it flows and stops puking air it is bleed. once car cools down coolant level may drop some so just top off.

There are aftermarket "speed bleeders" made that make for a simple, mess free, process also. these are not auto part store but sometimes sold on various LT1 forums in FS sections for around $20

 

Is there any chance you damaged the steam pipe that connects the back of the heads, whild you were working on the intake manifold?

How, exactly, did you do the throttle body coolant bypass?

 

your car "overheated" because air was in the system if you did not bleed it.

the leak at rear of motor most likely is the crossover steam pipe gaskets. each side takes 2 gaskets, one on each side of the steam pipe where the banjo bolt goes. dealer has them or some people use the oil drain plug gaskets the reight size (they look like a washer with rubber on them)

 

I got most of the air bleed after reading this. No way I damaged the steam pipe when I did intake. The bypass was done correctly looking at 3 different pictures with directions. So what are these gaskets I blew out and how do I fix them?

 

Thank you guys for the help so far

 

The gaskets are gasketed washers and there are 2 per head. One washer against the head and one on the outside of the steam pipe banjo fitting, so they kind of sandwich the banjo fitting agianst the head and seal it up. You can probably reach back there and try to see if it is leaking from the bolt area - maybe hold a paper towel back there and see where the coolant is coming from. One other alternative would be get some dye and blacklight for coolant leak detection - that would help you find the leak.

 

It only does it when it gets really hot. I ran it last night and let it get almost halfway and nothing. It was when it got to over half way up the temp gauge. I really don't want to over heat my car intentionally.

 

Buy or rent a pressure tester to help you find the leak.

 

I was chasing my tail over a water leak and wish I had done a pressure test because my new radiator had a leak on the upper drivers side that wouldn't show its self for 2 years.